Anti-annexin A5 antibodies in reproductive failures in relation to antiphospholipid antibodies and phosphatidylserine

PROBLEM: The presence of IgG anti-annexin A5 (IgGalphaA5) and/or antiphospholipid antibodies (aPL) are risk factors associated with recurrent spontaneous abortion. Problems are whether IgA anti-annexin A5 (IgAalphaA5) is pathogenic, and how IgGalphaA5 works. METHOD OF STUDY: Blood samples from 238 patients with early recurrent spontaneous abortion, 48 patients with recurrent in vitro fertilization-embryo transfer failure, 179 non-pregnant women and 120 pregnant controls were tested for IgAalphaA5 by enzyme-linked immunosorbent assay. We also determined if IgGalphaA5 appeared coincident with aPL. The antigenic epitope(s) recognized by IgGalphaA5 was investigated. RESULTS: We observed no difference between patients and controls for IgAalphaA5. The prevalence of IgGalphaA5 was not different statistically between patient samples with or without aPL. Patient IgGalphaA5 bound annexin A5 when the latter was free/unbound but not when annexin A5 was associated with phospholipid. CONCLUSIONS: The IgAalphaA5 does not appear to be pathogenic. IgGalphaA5 works to make a complex with annexin A5 without relation to aPLs, which may reduce annexin A5 available for binding to trophoblast.